X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml Date: Thu, 10 Aug 2006 12:55:39 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m27.mx.aol.com ([64.12.137.8] verified) by logan.com (CommuniGate Pro SMTP 5.1c.2) with ESMTP id 1316693 for lml@lancaironline.net; Thu, 10 Aug 2006 10:13:29 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.8; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m27.mx.aol.com (mail_out_v38_r7.6.) id q.bd6.2e7529f (39954) for ; Thu, 10 Aug 2006 10:12:32 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Thu, 10 Aug 2006 10:12:32 EDT Subject: Re: [LML] Re: Legacy Canopy X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1155219152" X-Mailer: 9.0 Security Edition for Windows sub 5330 X-Spam-Flag: NO -------------------------------1155219152 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 8/10/2006 2:09:11 A.M. Central Standard Time, kyrilian_av@yahoo.com writes: I've seen many references by Lancair builders that a prepreg is a sandwich of foam and symmetric layups of BID. On page 1-23 of the manual prepreg is defined as a honeycomb panel. ............. I've always understood prepreg to be stiff tacky cloth--carbon fiber or fiberglass--pre impregnated with epoxy, that must be refrigerated until shortly before use and heated to cure... Kyrilian, All of the comments are basically true. Post-cure heat is used to raise the future temperature at which the epoxy starts to soften. Such a temperature is much higher than wet lay-ups that are not heat-treated after curing. Panels, curved or flat, are stiffened by separating the BID skins with various materials. For example, single BID per side 1/4" thick flat panels are very light and probably not used structurally. Two BID per side 5/8" thick panels are very strong and much stiffer. Nomex honeycomb can be used because of its lightness, but it is less resistant to puncture wounds. High density foam can be stronger, stiffer and slightly heavier and is often used for upper wing surfaces near the aircraft entry so those stiletto heels won't cause a problem on that surface. Less dense foam can be used in other locations. The fuselage, bulkheads and ribs may utilize the Nomex, although current flanged ribs and bulkheads (similar to cap strip construction) tend to be made of just glass without intervening BID separation since the flange itself adds enough stiffness. All of these items are laid up in a mold (even the flat panels) where the final layers are dacron peel ply, cotton strips for air movement and plastic sheeting that is sealed at the edges and tapped for a vacuum to remove the air and squeeze everything together against the mold - thus vacuum bagging. The resulting pieces are generically called "prepreg" just like kleenex is used for every nose doily manufactured. Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) Abnegate Exigencies! -------------------------------1155219152 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 8/10/2006 2:09:11 A.M. Central Standard Time,=20 kyrilian_av@yahoo.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I've=20 seen many references by Lancair builders that a prepreg is a sandwich of f= oam=20 and symmetric layups of BID.  On page 1-23 of the manual prepreg is=20 defined as a honeycomb panel.  .............  I've always=20 understood prepreg to be stiff tacky cloth--carbon fiber or fiberglass--pr= e=20 impregnated with epoxy, that must be refrigerated until shortly before use= and=20 heated to cure...

 Kyrilian,
All of the comments are basically true.  Post-cure heat is used to= =20 raise the future temperature at which the epoxy starts to soften. Such=20= a=20 temperature is much higher than wet lay-ups that are not heat-treated a= fter=20 curing.  Panels, curved or flat, are stiffened by separating the B= ID=20 skins with various materials.  For example, single BID per side 1/4" th= ick=20 flat panels are very light and probably not used structurally.  Two BID= per=20 side 5/8" thick panels are very strong and much stiffer. 
 
Nomex honeycomb can be used because of its lightness, but it is le= ss=20 resistant to puncture wounds.  High density foam can be stronger,=20 stiffer and slightly heavier and is often used for upper wing surf= aces=20 near the aircraft entry so those stiletto heels won't cause a problem o= n=20 that surface.  Less dense foam can be used in other locations.  Th= e=20 fuselage, bulkheads and ribs may utilize the Nomex, although current=20 flanged ribs and bulkheads (similar to cap strip construction) tend to=20= be=20 made of just glass without intervening BID separation since the flange itsel= f=20 adds enough stiffness.
 
All of these items are laid up in a mold (even the flat panels) where t= he=20 final layers are dacron peel ply, cotton strips for air movement and plastic= =20 sheeting that is sealed at the edges and tapped for a vacuum to remove=20= the=20 air and squeeze everything together against the mold - thus vacuum=20 bagging.
 
The resulting pieces are generically called "prepreg" just like=20 kleenex is used for every nose doily manufactured.=20
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)

Abnegate Exigencies!
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